Thanks for reply. Here is feedback FB17549847. (Sorry for posting in Japanese)

Additional problem is here. When a second call comes in while the first one have answered and put on hold, pressing a button on the headset once (intended to answer the second call) will cause the following transactions: Transaction A: CXEndCallAction for first one, CXAnswerCallAction for second one Transaction B: CXEndCallAction for second one Transaction B is not expected to occur. Why is it happening?